This invention relates generally to field effect transistors and, particularly, to such transistors using nanotubes, such as carbon nanotubes.
Carbon nanotubes are graphene cylinders whose ends are closed by caps, including pentagonal rings. The nanotube is a hexagonal network of carbon atoms forming a seamless cylinder. These cylinders can be as little as a nanometer in diameter with lengths of tens of microns, in some cases. Depending on how they are made, the tubes can be multiple walled or single walled.
The drive current that is possible with a carbon nanotube transistor is insufficient for conventional logic applications. There are a number of reasons for this, including the fact that the drive current is too small for most logic circuit applications. While the drive current per unit width for carbon nanotube transistors may be high, due to the nano scale diameter of carbon nanotubes, the absolute current level is still not large enough for most logic applications.
Thus, there is a need for better ways to make carbon nanotube and other nanotube transistors.